Lubricating oil additives and compositions containing such additives

ABSTRACT

ESTERS OF 4-HYDROXY- AND 4-THIOL-BENZOIC ACIDS, DITHIO, 1,4-DIHYDRO-1-OXO-4-DITHIOMETHYLENEBENZENES AND 1,4DIHYDRO-1-OXO-4- (DITHIACYCLOPENT-2-YLIDENE)-BENZENES IN WHICH THE HYDROXY, THIOL AND OXO GROUPS ARE STERICALLY HINDERED ARE PROVIDED. ALSO PROVIDED ARE INTERMEDIATES FOR SUCH ESTERS AND SUBSTITUTED BENZENES. IN ADDITION, PROCESSES ARE PROVIDED FOR PREPARING THESE INTERMEDIATES FOR SUCH COMPOUNDS AND PROCESSES FOR PREPARING SUCH COMPOUNDS. THESE COMPOUNDS ARE MIXTURES THEREOF ARE USEFUL AS ADDITIVES FOR LUBRICATING OILS PROVIDING SUCH OILS WITH HIGH RESISTANCE TO OXIDATIVE CHANGE. IN ADDITION, OILS CONTAINING CERTAIN OF THE ESTERS, PARTICULAR BIS-ALKYLENE ESTERS, AND CERTAIN OF THE DITHIACYCLOPENTYLIDENE BENZENES AND MIXTURES THEREOF DEMONSTRATES SUPERIOR EXTREME PRESSURE LUBRICATING PROPERTIES.

United States Patent Oflice 3,778,370 Patented Dec. 11, 1973 ABSTRACT OFTHE DISCLOSURE Esters of 4-hydroxyand 4 thiol-benzoic acids, dithio,1,4-dihydro-1-oxo-4-dithiomethylenebenzenes and 1,4-dihydro-1-oxo-4-(dithiacyclopent-Z-ylidene)-benzenes in which thehydroxy, thiol and oxo groups are sterically hindered are provided. Alsoprovided are intermediates for such esters and substituted benzenes. Inaddition,

I processes are provided for preparing these intermediates for suchcompounds and processes for preparing such compounds. These compoundsand mixtures thereof are useful as additives for lubricating oilsproviding such oils with high resistance to oxidative change. Inaddition, oils containing certain of the esters, particular bis-alkyleneesters, and certain of the dithiacyclopentylidene benzenes and mixturesthereof demonstrate superior extreme pressure lubricating properties.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to compounds useful as additives for lubricating oilcompositions, to intermediates for such compounds, to processes forpreparing these compounds, and to lubricating oil compositionscontaining such compounds. Lubricating oils are employed in a host ofenvironments. Under most conditions of use, the oil comes into contactwith air, often at elevated temperatures and in the presence of metalsor chemical compounds which act as oxidation catalysts. Lubricatingoils, whether natural or synthetic, when exposed to such conditions,undergo a series of oxidation reactions. The deleterious efiects of suchoxidation includes an increase in viscosity, formation of carbonaceousmatter and the production of various oxygen-containing contaminants.Among others, the contaminants have been found to include lactones,ketones, aldehydes, esters, alcohols, hydroxy acids, anhydrides, andperoxides. The acidic and peroxidic contaminants attack metals, corrodebearings, and promote rust and wear. Acidic contaminants are also amajor source of the oil insolubles that cause ring sticking andsludging, and impede oil flow. Antioxidants are incorporated inlubricating oils to retard such oxidation of the oil.

As, the pressures or rubbing speeds between relatively moving surfacesincrease, the film of oil normally present between the surfaces issqueezed out or wiped away. When this occurs, hydrodynamic lubricationceases and boundary lubrication occurs. During boundary lubrication,metal-to-metal contact is experienced over a significant portion of thelubricated area. This contact often leads to excessive wear ordestruction of the relatively moving surfaces. Extreme pressureadditives are incorported in lubricating compositions to aid in thelubrication of moving metal surfaces under boundary lubricationconditions.

DESCRIPTION OF THE PRIOR ART Stevens et al., US. Pat. 2,265,582, issuedDec. 9, 1941, discloses tri-alkylated monohydroxy phenols having, in thepositions ortho to the hydroxy group, at least one alkyl groupcontaining three or more carbon atoms.

These phenols known as hindered phenols are said to inhibit oxidationalchanges in petroleum hydrocarbon products, when incorporated therein insmall amounts.

Humphreys et al., US. Pat. 2,073,841, issued Mar. 16, 1937, describesextreme pressure lubricating compositions containing esters andanhydrides of organic thio acids. Useful compounds are said to includes-ethyl thiobenzoate and benyl thiobenzoate.

Gompper and Toppl, Substituierte Dithiocarbonsauren and Ketenmercaptale,Berichte, 19 62, 95, 2861 disclose the reaction of active methylenecompounds such as cyanoacetamide with carbon disulfide followed byreaction with various halides to produce various dithio derivatives.

Andress, Jr., et al. US. Pat. 3,609,081, describes organic compositionssuch as lubricating oils and fuel oils containing secondary trialkylphenols in which the secondary alkyl groups contain from 6 to 9 carbonatoms. The phenols are described as antioxidants for the organiccompositions.

SUMMARY OF THE INVENTION The compounds of this invention comprise estersof 4-hydroxy and 4-thiol benzoic acids, dithio;1,4dihydrol-oxo-4-dithiomethylenebenzenes and 1,4-dihydro-l-oxo-4-(1,3-dithiacyclopent-Z-ylidene)benzenes having nuclear alkylsubstituents in both positions ortho to the hydroxy, thiol, and oxogroups which sterically hinder these groups.

These compounds are useful as additives for lubricating oilcompositions. The presence of these additives provides antioxidationprotection for the oil and, in many cases, additionally confers extremepressure lubricating properties to the oil.

DESCRIPTION OF THE INVENTION In a first embodiment novel esters of4-hydroxy and 4-thiol benzoic acids, diothio, novel 1,4-dihydro-1-oxo-4-dithiomethylenebenzenes and novel 1,4-dihydro-l-oxo-4-(1,3-dithiacyclopent-Z-ylidene)benzenes having nuclear alkylsubstituents in both positions ortho to the hydroxy, thiol and oxogroups which sterically hinder these groups are provided.

The esters and substituted benzenes of this invention are derived from4-hydroxy and 4-thiol benzoic acids, dithio. The benzoic acid moiety issubstituted in both positions ortho to the hydroxy and thiol groups withalkyl substituents which sterically hinder the hydroxy and thiol groups.Such alkyl substituents have four or more carbon atoms and are generallybranched rather than straight chain, e.g., t-butyl, t-amyl and the like.

Preferred compounds of the invention include esters of 4-hydroxy and4-thiol benzoic acids, dithio having the following formulae:

( i tY 1,4-dihydro-1-oxo-4-dithiomethylenebenzenes having the followingformula:

and 1,4 dihydro-1-oxo-4- (1,3-dithiacyc1opent-2-ylidene) benzenes havingthe following formula:

In the above Formulae I, II, III, and IV:

(1) R and R each represent an alkyl group, which sterically hinders theadjacent hydroxy, thiol, or x0 group, containing four or more carbonatoms, desirably four to nine carbon atoms in a branched chain, such ast-butyl, t-amyl, s-hexyl, s-heptyl, s-octyl, s-nonyl and the like;

(2) R R and R each represent alkyl containing from 1 to 20 carbon atomssuch as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl,tert-butyl, pentyl, iso-amyl, tert-amyl, hexyl, heptyl, octyl, nonyl,dccyl, dodecyl, pentadecyl, eicosyl and the like; hydroxyalkyl, e.g.,--R-OH, hydroxyalkyloxyalkyl, e.g.,

in which the alkylene moieties represented by R contain 2 to 5 carbonatoms and can be straight or branched chain such as ethylene,1,2-propylene, 1,2-butylene, 1,2-pentylene and the like and n represent2 to 6; aralkyl such as benzyl, p-xylyl, and the like; or aryl such asphenyl, 4-tolyl and the like;

(3) R represents an alkylene group containing from 1 to 8 carbon atomssuch as methylene, ethylene, trimethylene, tetramethylene,pentamethylene, hexamethylene, heptamethylene, octamethylene, and thelike;

(4) Each R represents hydrogen, alkyl such as defined above for R oraryl such as phenyl, tolyl, xylyl and the like, and preferably Rrepresents hydrogen;

(5) X represents oxygen or sulfur and preferably oxygen; and

(6) Y represents hydrogen or a metallic cation such as those derivedfrom alkali metal such as sodium and potassium and those derived fromalkali earth metals such as calcium and barium; preferably Y representshydrogen.

4 TABLE A Illustrative of the esters of benzoic acid, dithiocontemplated by the invention are the following typical compounds:

Illustrative of the methylenebenzenes contemplated by the invention arethe following typical compounds:

(XII) 1,4-dihydro-l-oxo-2,6-di-t-butyl-4-dimethylthiomethylenebenzene(XHI) 1,4-dihydro-1-thione-2,6-di-t-butyl-4-dimethylthiomethylenebenzene(XIV) l,4-dihydro-l-oxo-2,6-di-t-butyl-4-di-n-octylthiomethylenebenzene(XV)1,4-dihydro-1-oxo-2,6-di-t-amyl-4-di-hydroxypropylenethiomethylenebenzene(XVI)1,4-dihydro-1-oxo-2,6-di-t-butyl-4-di-hydroxypropylenethiomethylenebenzeneIllustrative of the dithiacyclopent-ylidenebenzene contemplated by theinvention are the following typical compounds:

(XVII)l,4-dihydro-1-oxo-2,6-di-t-butyl-4-(1,3-dithiacyclopent-2-ylidene)-benzene (XVIII) 1,4-dihydro-1-oxo-2,6-di-t-butyl-4-(4-methyl-1,3-dithiacyclopent-2-ylidene)-benzene (XIX)1,4-dihydro-1-oxo-2,6-di-t-amy1-4-(1,3-dithiacyclopent-Z-ylidene)benzeneIn a second embodiment of this invention intermediates for the abovedithiobenzoic acid esters and substituted benzenes are provided whichcomprise 4-thiol and 4-hydroxybenzoic acids, dithio, in which the acidshave nuclear alkyl substituents in both positions ortho to the hydroxyand thiol groups which sterically hinder such hydroxy and thiol groups.

Preferred intermediates of this invention include 4-thiol and4-hydroxybenzoic acids having the following formula:

( JIIY s SY wherein X, Y, R and R have the same meaning as definedabove.

In a third embodiment of this invention, processes are provided forpreparing the above-described 4-thiol and 4-hydroxybenzoic acid, dithio,intermediates which comprise combining about one equivalent of a phenolor thiophenol having nuclear alkyl substituents in both positions orthoto the hydroxy or thiol group which sterically hinder the hydroxy orthiol group with about two ventiom r equivalents of a strong protonacceptor to obtain a first reaction product. This first product is thencombined with about one equivalent of carbon disulfide to yield theintermediate as a dithiobenzoic acid radical.

This acid radical is probably in the form of the double salt of thecation of the proton acceptor. The dithiobenzoic acid can be recovered,if desired, by acidifying the reaction mixture with at least twoequivalents of a proton donor such as a mineral acid to yield thedithiobenzoic acid in free acid form. However, it is generally moreconvenient to simply use the acid in its radical form without recoveryfrom the reaction mixture as the intermediate for preparing thecompounds of this in- As used herein and in the appended claims, theterm strong proton acceptor refers to a moiety capable of extracting aproton from the para position of the sterically hindered phenols andthiophenols used to prepare the intermediates described above and shownin Formula V. Such proton acceptors are well known and include alkalimetal hydroxides such as sodium and potassium hydroxide, alkali metalalkoxides such as sodium and po' tassium methoxide and ethoxide andalkali metal amides such as sodium and potassium amide.

The above process is preferably carried out in a solvent medium under aninert atmosphere. The solvent can be any inert solvent which does notinterfere with the desired reactions. The solvents can be polar as wellas non-polar. Generally, mixtures of polar and non-polar solvents areused in order to obtain at least partial miscibility of the variousreactants. For example, a mixture of water, dimethyl sulfoxide andpentane, hexane or heptane is conveniently used. The inert atmospherecan be any atmosphere which does not interfere with the reaction. It ismost conveniently nitrogen.

The reactions are carried out at low to moderate temperatures, e.g.,from about 0 C. to about 50 C. and preferably from about 10 C. to about40 C.

In a fourth embodiment of this invention, processes are provided forpreparing the esters of dithiobenzoic acid and the substituted benzenesdescribed above and exemplified in Formulas I-IV. These processescomprise combining the dithiobenzoic acid intermediate described abovein its radical form with zero to one equivalent of a proton donor toobtain a third reaction product. This third reaction product is thencombined with a two to one-half equivalents of a precursor of thedesired thio substituent.

The quantity of proton donor with which the intermediate radical iscombined is determined by the product desired. If the product desired isof the diester type represented by Formula III above or thecyclopentylidenebenzene of Formula IV above, the intermediate is notreacted with the proton donor. This double salt is thereby free to reactwith two equivalents of the precursor of the thio substituents. Theprecursor has only one reactive site or one equivalent if it has tworeactive sites. If the. product is of the mono ester of the typerepresented byFormulas I and 11 above, then the intermediate is combinedwith one equivalent of the proton donor. This product is then free toreact with one equivalent of thio substituent precursor if suchprecursor has one reactive site or one-half equivalent if the precursorhas two reactive sites as in the case of the dihaloalkanes from whichthe. compounds of Formula II are prepared. However, see the discussionbelow concerning when the precursor is a dihaloalkane wherein the halosubstituents are on adjacent carbon atoms.

The term proton donor" as used herein and in the appended claims, refersto a moiety capable of donating a proton to the thiobenzoic acidradical. These proton donors are conveniently strong mineral acids suchas hydrochloric acid, sulfuric acid and nitric acid.

The precursors of the thio substituent are alkanes, hydroxyalkanes,hydroxyalkyloxyalkanes, hydroxyalkyl poly (oxalkyl) oxyalkanes andaralkanes substituted with at least one moiety which causes them to bereactive toward the dithiobenzoic acid radical. Conveniently thesesubstituents are halogen and preferably chlorine. The precursors aresubstituted with one halo group except for those precursors used toprepare the esters of Formula II and thedithiacyclopent-Z-ylidenebenzenes. The precursors for these two types ofcompounds contain two halo substituents. The process of adding theproton donor to the dithiobenzoic acid radical can be carried out atvarying temperatures; however, room temperature is quite convenient.

The process of esterifying the dithiobenzoic acid radical with the thiosubstituent precursor can also be carried 7 out over a wide temperaturerange suitably ranging from about room temperature up to about 100 C. orgreater. Preferably, the reaction is carried out by combining thedithiobenzoic acid radical and the thio substituent precursor at aboutroom temperature and heating the reaction mixture with stirring to about50 to about C.

The time required for the reaction to proceed to completion can varywidely depending upon temperatures, concentrations, etc. Typically, thereaction will proceed to completion within about one to five hours whencarried out in preferred temperature range.

In the preparation of the his esters such as Compound X fromdihaloalkanes having the halo substituents on adjacent carbon atoms, ithas been found a large amount of the correspondingdithiacyclopent-Z-ylidenebenzene is formed.

Without desiring to be bound by such speculation, it might be postulatedthat the intermediate formed upon reaction of one equivalent ofdihaloalkane with one equivalent of the benzoic acid, dithio, radicalcould react as follows:

As can readily be seen the possible products which could be formed arenot limited to the two products shown above. Yet another product mightbe a carbon sulfur polymer type chain having the oxobenzene groupspendant therefrom. Other products can also be envisioned.

Of this multiplicity of possible products, only two have beenidentified, namely the two products from Reactions A and B above. Thenon-purified reaction product obtained as described below andexemplified by Example VII, when added to a lubricating oil as describedbelow, results in a composition having quite superior extreme pressurelubricating properties as well as high resistance to oxidative change.However, when the product of Reaction B above is isolated and added to alubricating oil, the composition does not have nearly as good extremepressure lubricating properties as the composition prepared from theunpurified reaction product.

What this unpurified reaction product contains to cause the lubricatingoils to which it is added to have the superior extreme pressurelubricating properties is unknown. Again without wishing to be bound byspeculation, it might be the synergistic efiect of the combination thehis ester (Reaction A above) and the dithiacyclopent- 2-ylidenebenzene(Reaction B above) or it might be an as yet unidentified third componentor some combination of these possibilities.

In a fifth embodiment, lubricating oil compositions are providedcomprising a major amount of an oil of lubricating viscosity and aneffective amount of a compound selected from the class consisting ofesters of 4-hydroxybenzoic acids, dithio; esters of 4-thiolbenzoicacids, dithio; 1,4-dihydro-1-oxo 4 dithiomethylenebenzenes and 1,4-dihydrol-oxo-4 (1,3-dithiacyclopent-2 y1idene)benzenes in which theesters and benzenes have nuclear alkyl substituents in both positionsortho to the hydroxy, thiol, or x0 groups which sterically hinder suchgroups. Preferably, the lubricating oil compositions of this inventioncomprise a major amount of an oil of lubricating viscosity and aneffective amount of one or more of the compounds of Formulas IIV.

The esters and benzenes are present in the lubricating oil compositionin an amount effective to impart the desired antioxidation and extremepressure lubrication properties. This amount can range from about 0.1percent weight to about percent weight of the total oil composition andgenerally from about 0.5 percent weight to about 3 percent weight of thetotal oil composition.

In general, solutions of the esters and benzenes in oil are more readilyobtained when the groups represented by R R and R in the above formulaeare oleophilic in nature, e.g., have medium length or longer alkylchains such as octyl, decyl, dodecyl eicosyl, and the like or have ahigher number of oxyalkyl units in the hydroxalkyl poly(oxyalkyl) chain.

It has been found that the hydroxyalkyl substituted compounds and higherhomologs tend to be crystalline in nature.

In some instances, for example, where these compounds are used in higherconcentrations, e.g., 2-5 percent weight of the total oil composition,they may be diflicult to dissolve in the oil and occasionally maycrystallize out of the oil. These crystallinity problems generally arereadily overcome by using a mixture of hydroxyalkyls having a varyingnumber oxyalkyl units in the chain such as a mixture of esters havingabout one-half each of a hydroxyalkyloxyalkyl and ahydroxyalkyl-di-oxyalkyl substituent.

8 The esters and benzenes can be added to the oil singly or in mixtures.For example, a mixture of two or more esters can be used. Alternatively,a mixture of two or more benzenes or a mixture of esters and benzenescan be used. It may be noted that the benzenes are, in a sense, a doubleesterification product obtained from the synthesis of the ester. Oftenvarying quantities of esters of benzenes are produced as impuritiesduring the synthesis of the other type of compound. It is generally mostconvenient to simply use the mixture obtained without attempting aseparation of the compounds.

OTHER ADDITIV ES Other additives may also be included in the oilcomposition to fulfill functions other than those provided by the estersand benzenes as well as to augment the functions of the latteradditives.

The other additives can be present in varying amounts. Usually, for oilsto be used in an engine, the total amount of these additives will rangefrom about 0.1 to 15 weight percent and more usually from about 0.5 to10 weight percent. The individual additives may vary in amount fromabout 0.01 to 10 percent weight of the total composition.

These additives include ashless dispersants such as succinimides,hydrocarbyl alkylene polyamines, etc., corrosion inhibitors such asmetal dithiophosphates, etc., detergents such as the sulfonates,phosphonates, phenates, etc., viscosity index improvers such as thepolyisobutylenes, polyacrylates, etc., pour point depressants such asthe polymethacrylates, polyacrylamides, etc., extreme pressureadditives, and other additives designed to accomplish specificobjectives.

LUBRICATING OILS The oils which find use in this invention are oils oflubricating viscosity derived from petroleum or synthetic sources. Theoils can be paraffinic, esters, naphthenic, halo-substitutedhydrocarbons, asphaltic or combinations thereof. Oils of lubricatingviscosity normally have viscosities in the range of 35 to 50,000 SayboltUniversal Seconds (SUS) at 100 F. and more usually from about 50 to10,000 SUS at 100 F.

The following examples are included to further illustrate but not limitthe invention.

EXAMPLE I OXIDATOR B TEST The stability of an oil composition againstoxidative change is measured by the time required for the consumption ofone (1) liter of oxygen by 100 grams of the test oil at 340 F. (171 C.).For covenience the actual test uses 25 grams of oil and the results arecorrected to a IOO-gram sample. A catalyst containing a mixture ofsoluble salts is added to the oil which provides parts per million(p.p.m.) copper, 80 p.p.m. iron, 4.8 p.p.m. manganese, 1100 p.p.m. leadand 49 p.p.m. tin. The test can be continued for a total of 10 hours andthe number of liters of oxygen taken up in this period is reported. Inaddition, the viscosity of the oil is measured at the start of the testand at the end of the l0-hour period. The increase is reported as apercentage of the original value. Table I reports the values obtainedfrom subjecting a variety of oil compositions to the Oxidator B test.The amount of each additive used is expressed as percent weight of thetotal composition. The oil used in these tests is a solvent refinedneutral hydrocarbon oil having a viscosity of 480 Saybolt UniversalsSeconds at F. (38 C.).

TABLE I.OXIDATOR B TEST Additive oi the Other additives,

invention percent weight Lifetime Comhrs. for 1 Oz uptake, Vis poundliter liters/ increase, No. Percent, wt. A B C D E uptake hours percentmuwvoucl en mall.

1 Other additives:

A=2,2-bls(l-hydroxy-i-polypropylenephenyl)disulflde 75 percent weight inoil. B=air-bis(l-hydroxy-c-methyl-4-polypropyienepheny0disuifide, 76percent weight in o C=A polyisobutenylsucclnimide produced by reacting asuccinic anhydrlde of a polybutene (PIBSA 950) having a number averagemolecular weight of about 950 with tetraethylenepentamine (TEPA) at amole ratio of TEPA to PIBSA of 0.87, approximately 44 percent weightactive additive in oil solution.

D =Terephthalie acid.

E=99.3 percent weight of a pol sobutenylsuccinimide similar to that ofCompound 0 except that succinic anhy ride oi a polybutene (PIBSA 640)having a number average molecular weight oi. about 640 is used to reducethe mole ratio oi TEPA to total PIB SA to 0.50, and 0.7 Eercent weightof terephthalic acid.

F=Bis(3,5-di-t-butyl-4-hydroxyp enyDmethylene-au antioxidant currentlyin commercial use and used as a reference in the above tests.

! Reaction product obtained from Example VII below.

' See Table A above.

From the above results it can be Seen the O l C P permit loadings inexcess of 3000 pounds. The results of {ions of the invention exhibit atleast as much and gcntesting oil compositions of this invention asdescribed erally greater resistance to oxidativc change than the bov aret f th i T bl 11A, reference oil composition.

TA L EXAMPLE IIFALEX EXTREME PRESSURE TEST B E FALEX EXTREME PRESSURETEST The capability of a lubricating oil composition to lubri- Oil No.Shearload, lbs. Oil No. Shear load, lbs. cate under extreme pressurescan be measured by this 1 575 1 600 test. The Falex machine ismanufactured by the Faville- 11300 [Le Vally Corporation of Chicago,111. In this test, two .2% 8 opposing stationary V-blocks are pressed bya nutcracker 113001 1: arrangement of lever arms toward each otheragainst an 5%,223" interposed rotating steel shaft. The rotating shaftis 4,150

driven by a chuck through a brass shear pin. The V-block and pin testspecimens are immersed in a vessel of test lubricant at a preselectedtemperature. The machine is Q2%? 6 $}:f g figg ifgg lggggggfifs figgfgggi fi g 3 352 3 operated at 290 r.p.m. and the specimens are broken inusedln these tests. Seizure did not occur under maximum loading.

at 300 pounds loading. During the test, loading between the. V-blocksand the pin is increased automatically until seizure occurs. Thisfailure point is indicated by shearing 0f the brass pin holding therotating shaft. The load at In the above Falex test all compositions ofthe invention exhibited extreme pressure lubricating properties equal toand in many cases markedly superior to the failure in pounds is taken asa quantitaive measure of the refefePce 011 Fomposition Composition 20extreme pressure properties of the oil composition. Min- @XhlbltedPamculafly Outstanding extreme PTBSSIIFe P P' l il may f il t 600 t 900nd oil i h d erties and the results of further testing of the reactionateextreme pressure additives will fail at 1000-2000 p uct from ExampleVII with other additive combinapoundszand very effective extremepressure additives will tions is shown in Table IIB.

TABLE IIB.FALEX EXTREME PRESSURE TEST Oil No.

Additive 1 i 1 In the same 4.80 8138 neutral oil as above examples.

1 See Example 1 for composition of Additives C and D.

' Additives are expressed as percent weight of the total oilcomposition. Additive F=Same as E except does not contain terephthalicacid.

5 Additive G=Tetrapropenylsuccinic acid.

Reaction product from Example VIL The results shown in Table IIB abovedemonstrate that the reaction product of Example VII both alone and incombination with other additives enhances the extreme pressurelubrication properties of the oil. It may be noted that Oil No. 28containing only Additive G, an acidic species, performed no better thanthe base oil which, as stated above, usually results in seizure at about600 to 900 pounds loading. It may also be noted that Oil No. 30containing only the reaction product from Example VII resulted inextreme pressure lubrication to loadings approximately 50 percent largerthan the base oil either with or without Additive G. However, Oil Nos.25, 27 and 29, which contain both the reaction product of Example VIIand an acid species (Additives D or G), gave extreme pressurelubrication to greatly increased loadings and in one case (Oil No. 25)to the limits of the machines.

EXAMPLE III-BEARING CORROSION TEST In addition to conferring beneficialproperties to lubrieating oils, additives must not cause certain harmfuleffects. One harmful effect to be avoided is corrosion of engine parts,particularly the nonferrous parts which come in contact with the oil.Corrosion of this nature caused by a particular additive is measured byimmersing separate strips of lead and copper in the oil composition tobe tested and maintaining the 'oil at a temperature of 295 F. (146 C.)for 20 hours. Both strips are weighed to determine weight loss. Inaddition, the copper strip is washed with potassium cyanide solution toremove copper compound deposits and re-weighed. The results of testingseveral additive combinations of the invention are shown below in TableHI. The base oil used is the same 480 SUS neutral oil used in the aboveexamples.

1 See previous examples for compositions.

Reported as milligrams lost.

1 Reported as B/A B=Cu loss before KCN wash and A=Cu loss after KCNwash.

Same composition as 9 and 20 respectively except without Additive D.

Although the above data, particularly the results from Oil Nos. 9, 9-A,20 and 20-A, do not conclusively demonstrate the necessity for thepresence of a mild organic acid species to retard nonferrous corrosion,the results do appear to demonstrate there is no adverse effects fromhaving the acid species present. This is desirable since the presence ofthese acid species enhance the extreme pressure lubrication propertiesof the oil as shown in Table IIB above.

The following Examples IV, V, and VI demonstrate the preparation ofthree compounds useful as antioxidants in extreme pressure additives inthe compositions of this invention. The preparation of the threecompounds is the same up to a point as set forth below under the headingof General Preparation of Additive Intermediate.

General preparation of additive intermediate To a 500-ml. 3-neck flaskequipped with stirrer, thermometer, nitrogen bleed, dropping funnel andcondensor is added 2,6-di-t-butylphenol (20.6, 0.1 mole) in dimethylsulfoxide (50 ml.). A solution of potassium hydroxide (13.2 g., 0.2.mole) in water (15 ml.) is prepared, cooled and diluted with dimethylsulfoxide. This solution is added to the phenolic solution above withstirring under a nitrogen blanket. The solution is cooled to 10 C. 5with an ice water bath and carbon disulfide (7.6 g., 0.1 mole) is addedto the stirred'solution while maintaining the temperature at 10 C.Stirring is continued at 10 C. for 30 minutes after addition iscomplete. Cooling is discontinued and the temperature of the stirredsolution is allowed to rise to room temperature. At this point, thesynthesis is continued with the nonisolated intermediate as shown inExamples IV, V, and VI below.

EXAMPLE IV Preparation of Compound III-3,5-di-t-butyl-4- hydroxybenzoicacid, dithiol-n-octyl ester To the nonisolated intermediate preparedaccording to the general preparation above is added concentratedhydrochloric acid (10 ml.) slowly with stirring followed by the additionof l-bromo octane (19.3 g., 0.1 mole). Stirring is continued for onehour at room temperature. The temperature is raised to 70 C.i10 for onehour. The reaction mixture is then cooled and poured into ice water (500ml.) with stirring to yield a liquid product. The aqueous mixture isextracted three times with a 200 ml. of ether. The combined organicphases are dried over anhydrous sodium sulfate and the solvent isremoved under vacuum on a rotary evaporator to yield 35.4 grams ofproduct suitable for use without further purification. Recrystallizationof a portion of the product from mixed hexanes yields a red crystallinesolid. Elemental analysis sulfurfound=16.3% w.; calculated 16.2% w.

EXAMPLE V Preparation of Compound XII1,4-dihydro-l-ox0-2,6-di-t-butyl-4-dimethylthiomethylenebenzene To the nonisolatedintermediate obtained from the general preparation above is addediodomethane (28.4 g., 0.2

mole) slowly with stirring. Stirring is continued at room temperaturefor one hour followed by heading to 70 0.:10" for one hour. The reactionmixture is cooled to room temperature and 200 ml. of water is addedfollowed by stirring for an additional 15 minutes. The aqueous mixtureis extracted with ether (250 ml.) three times. The combined organicphases are dried over anhydrous sodium sulfate and the solvent isremoved on a rotary evaporator to yield 24.4 grams of product suitablefor use without futher purification.

EXAMPLE VI Preparation of Compound IXbis(3,5-di-t-butyl-4-hydroxybenzoic acid, dithio)methylene ester To the nonisolatedintermediate obtained from the general preparation above is addeddiiodomethane (13.4 g., 0.05 mole) and stirring is continued at roomtemperature for one hour followed 'by heating to 70 C.- -l0 for onehour. The reaction mixture is cooled and poured into ice water (500 ml.)with stirring. The aqueous mixture is extracted three times with ether(200 ml.). The combined organic phases are dried over anhydrous sodiumsulfate, filtered and the solvents are removed on a rotary evaporator.The solid product obtained is dissolved in a mixed hexanes solvent toproduce a saturated solution. The solution is chilled in a refrigeratorovernight. The mother liquor is decantered from the crystals obtainedand the crystals are taken up in 750 m1. of mixed hexanes. The volume ofthe second solultion is reduced to about half and cooled to obtaincrystallization. The crystals thus obtained are suitable for use as alubricating oil additive.

EXAMPLE VII Preparation of Compound Xbis(3,5-di-t-butyl-4-hydroxybenzoic acid, dithio)ethylene ester To a l-liter flask equippedwith a stirrer, thermometer, nitrogen-bleed, dropping funnel andcondensor is added 2,6-di-t-butylphenol (61.8 g., 0.3 mole) in dimethylsulfoxide (75 ml.) and hexane (75 ml.). A solution of potas- 13 siumhydroxide (39.6 g., 0.6 mole) in water (45 ml.) is prepared, cooled anddiluted with dimethyl sulfoxide (25 ml.). This solution is added to thephenolic solution above with stirring under a nitrogen blanket. Thesolution temperature is maintained at 30 :5. The solution turned green."While maintaining this temperature, carbon disulfide (23 g., 0.3 mole)is added with stirring. Stirring is continued at room temperature forone hour during which time the reaction mixture turned deep red. 'Whilemaintaining the temperature at 30 C., as above, concentratedhydrochloricacid (30 ml.) is added, followed by addition of ethylenedichloride (14.8 g., 0.15 mole). The reaction mixture is heated to 70C.'il0 C. for one hour followed by cooling to40 C. Distilled water (300ml.) is

added and the reaction'mixture is stirred for five minutes. The reactionmixture is placed in a separatory funnel and the organic phase isremoved. Distilled water (500 ml.) is added to the remaining aqueousphase, which is then extracted three times with Chevron Thinner 250*(600 ml.). The combined organic phases are washed three times with water(700 ml.) and are dried over anhydrous sodium sulphate. The organicphase is filtered and the volatiles are removed under vacuum on a rotaryevaporator to yield 73.4 g. of product suitable for use without furtherpurification.

Subsequent analysis of the reaction product obtained above demonstratesthat it contains significant portions of Compound X, the bis-ethyleneester, and Compound XVII, the dithiacyclopentylidenebenzene, thestructures of which were confirmed by nuclear magnetic resonancespectroscopy.

Compound XVII, the dithiacyclopentylidenebenzene was recovered and wastested in the Oxidator B and Falex Extreme Pressure tests describedabove. The results obtained were not as good as those obtained from theuse of the crude reaction mixture as the lubricating oil additive.

What isclaimed is:

1. A lubricating oil composition comprising:

(a) a major amount of an oil of lubricating viscosity;

and

(b) an amount effective to impart antioxidation and extreme pressurelubrication properties to said oil of a compound having one of thefollowing formulae:

*Chevron Thinner 250 is a high-aniline water-white petroleum naphthaavailable from Standard Oil Company of California.

wherein:

(1) R and R each represent an alkyl group which sterically hinders theadjacent hydroxy, thiol or 0x0 group;

(2) R R and R each represent alkyl, hydroxyalkyl, hydroxyalkyloxyalkyl,hydroxyalkylpoly- (oxyalkyl), aralkyl or aryl;

(3) R represents an alkylene group;

(4) each R represents hydrogen, alkyl or aryl;

(5) X represents oxygen or sulfur; and

(6) Y represents hydrogen or a metallic cation selected from alkalimetal and alkaline earth metal cations.

A lubricating oil composition of claim 1 wherein:

(1) R and R each represent a branched alkyl containing from 4 to 10carbon atoms;

(2) R R and R each represent alkyl containing from 1 to 20 carbon atoms,a hydroxyalkyl containing from 2 to 5 carbon atoms, ahydroxyalkyloxyalkyl containing from 4 to 10 carbon atoms, ahydroxyalkylpoly(oxyalkyl) containing 2 to 5 carbon atoms in each alkylmoiety and from 2 to 5 oxyalkyl units, aralkyl containing 7 to 8 carbonatoms or aryl containing 6 to 7 carbon atoms;

(3) R represents an alkylene group containing from 1 to 8 carbon atoms;

(4) each R7 represents hydrogen; and said oil contains from 0.1 to 5percent weight of said compound.

A lubricating oil composition comprising:

(a) a major amount of an oil of lubricating viscosity;

and

(b) an amount of eifective to impart antioxidation and extreme pressurelubrication properties to said oil of a lubricating oil additive whichis the fourth reaction product formed by:

(1) combining in an inert solvent and under an inert atmosphere (a)about one equivalent of a phenol having nuclear alkyl substituents inboth positions ortho to the hydroxy group which sterically hinder saidhydroxy group with (b) about two equivalents of a proton acceptorselected from alkali metal hydroxides, alkoxides and amides to obtain afirst reaction product;

(2) combining said first reaction product with about one equivalent ofcarbon disulfide to ob tain a second reaction product;

wherein Steps (1) and (2) are conducted at a temperature of from 0 C. to50 C.,

(3) combining at from room temperature up to 30 C. said second reactionproduct with about one equivalent of a proton donor selected fromhydrochloric acid, sulfuric acid and nitric acid to obtain a thirdreaction product; and

(4) combining at from room temperature up to C. said third reactionproduct with about one-half equivalent of a dihaloalkane containing atleast two carbon atoms in which the halogen substituents are on adjacentcarbon atoms to obtain said fourth reaction product.

4. A lubricating oil composition of claim 3 wherein said dihaloalkane isa dichloroalkane containing from 2 '16 References Cited UNITED STATESPATENTS to 30 carbon atoms and said oil contains from 0.1 to 5 per-2,073,841 3/1937 Humphreys et aL cent of said fourth reaction product.

5. A lubricating oil composition of claim 3 wherein 5 FOREIGN PATENTS665,107 1/1962 Great Britain 25242.7

said dihaloalkane is a dichloroalkane containing from 2 to 8 carbonatoms and said oil contains from 0.1 to 5 percent of said fourthreaction product.

6. A lubricating oil composition of claim 3 wherein said diahaloalkaneis 1,2-dich1oroethane and said oil contains from 0.5 to 3 percent ofsaid fourth reaction product.

DANIEL E. WYMAN, Primary Examiner 10 A. H. METZ, Assistant Examiner US.Cl. X.R.

25246.7, 48.2, 400 R, 406; 260-327 M, 455 R

